Approaches for large-area a-SiC:H photovoltaic-powered electrochromic window coatings

We have fabricated 16 cm(2) monolithic, electrochromic (EC) window-coating devices powered by integral semitransparent amorphous silicon carbide (a-SiC:H) photovoltaics (PV). Self-powered PV-EC windows could modulate solar gain in buildings, thereby reducing both heating and cooling requirements. In preparation for work on large-area PV-EC devices, we examined several important new issues. The first issue is control of pinhole shunt density in the PV portion of the coating, and the second is resistive power loss in the transparent conductor contact layers. Adapting an electrochemical process previously demonstrated in a-Si:H, we have been able to electrically isolate shunts in our a-SiC:H devices. We propose a new design for scribing and bus bar connections that can reduce the resistive losses on large area TCO without greatly affecting window appearance. (C) 2000 Elsevier Science B.V. All rights reserved.